Dog Age Calculator
Convert your dog's age to human years based on size and breed with scientific accuracy
Calculate Your Dog's Human Age
Enter age in years (e.g., 1.5 for 1 year and 6 months)
Select based on adult weight
Labrador uses scientifically-proven formula from UC San Diego research
Age Conversion Results
Dog Size: Medium
Breed: Other/Mixed
Calculation Method: Size-based Conversion
Formula: Progressive aging rates
Example Calculation
5-Year-Old Medium Dog Example
Dog: 5 years old, Medium size (30 lbs)
Calculation:
• First year: 15 human years
• Second year: +9 human years (total: 24)
• Years 3-5: 3 × 5 = +15 human years (medium dog rate)
Total: 15 + 9 + 15 = 39 human years
3-Year-Old Labrador Example (Scientific)
Using UC San Diego research formula:
Human age = 16 × ln(3) + 31
Human age = 16 × 1.099 + 31
Human age = 48.6 ≈ 49 years
Dog Life Stages
Puppy
0-1 years
Growth and development
Young Adult
1-2 years
High energy and learning
Adult
2-7 years
Prime physical condition
Senior
7-10 years
Slowing down, health monitoring
Geriatric
10+ years
Special care needed
Dog Size Categories
Small Dogs (≤20 lbs)
Chihuahua, Pomeranian, Yorkshire Terrier
Live longer, age slower after 2 years
Medium Dogs (21-50 lbs)
Border Collie, Cocker Spaniel, Bulldog
Moderate aging rate
Large Dogs (>50 lbs)
German Shepherd, Labrador, Golden Retriever
Age faster, shorter lifespan
Understanding Dog Age Conversion
Why the 7-Year Rule is Wrong
The old "1 dog year = 7 human years" rule is overly simplistic. Dogs age much faster when young and slower when mature. The first year is equivalent to about 15 human years, and aging rates vary significantly by size.
Scientific Approach
- •First year: 15 human years (rapid development)
- •Second year: Additional 9 human years
- •Subsequent years: 4-6 human years (size-dependent)
- •Smaller breeds live longer and age slower
Labrador Research Formula
Human Age = 16 × ln(Dog Age) + 31
University of California, San Diego researchers studied 104 Labradors and published this scientifically-proven formula in 2019. It's based on DNA methylation patterns.
Size-Based Aging Rates
- Small dogs (≤20 lbs): 4 human years per dog year
- Medium dogs (21-50 lbs): 5 human years per dog year
- Large dogs (>50 lbs): 6 human years per dog year
Note: This calculator accounts for both size-based aging and the scientific Labrador formula for the most accurate age conversion.